Mobile communication devices have become increasingly common in current society for providing wireless communication services. The prevalence of these mobile communication devices is driven in part by the many functions that are now enabled on such devices. Increased processing capabilities in such devices means that mobile communication devices have evolved from being pure communication tools into sophisticated mobile multimedia centers that enable enhanced user experiences.
The redefined user experience requires higher data rates offered by wireless communication technologies, such as long-term evolution (LTE). Particularly in light of carrier aggregation (CA) schemes supported by modern cellular communications networks, a mobile communication device can be configured to simultaneously transmit an outgoing radio frequency (RF) signal(s) in multiple uplink frequency bands, while receiving an incoming RF signal(s) in multiple downlink frequency bands. Support for the multiple frequency bands is provided by multiple radio front-ends, each supporting one or more frequency bands. The radio front-ends are connected to a common antenna via a multiplexer (e.g., a diplexer for the dual-band scenario or a triplexer for a tri-band scenario).
However, the mobile communication device may employ many nonlinear components/circuitries (e.g., power amplifier, filter, multiplexer, and switch) in a transmission path of the outgoing RF signal(s). As a result, the nonlinear elements/circuitries can create an intermodulation distortion (IMD) product(s) in the outgoing RF signal(s). Moreover, the IMD product(s) may fall into an adjacent downlink frequency band for receiving the incoming RF signal(s), thus causing degradation in the incoming RF signal(s). For example, in an uplink CA (ULCA) mode, the mobile communication device may simultaneously transmit the outgoing RF signal(s) in LTE uplink band one (1) (1920-1980 MHz) and LTE uplink band three (3) (1710-1785 MHz), while receiving the incoming RF signal(s) in LTE downlink band 1 (2110-2170 MHz) and LTE downlink band 3 (1805-1880 MHz). In this regard, a third-order IMD (IMD3) product may be created through intermodulation between the outgoing RF signal(s) transmitted in LTE uplink bands 1 and 3, which falls into the frequency range of LTE downlink band 1. As a result, the mobile communication device(s) may have difficulty in receiving the incoming RF signal in LTE downlink band 1. Notably, similar issue may also exist between LTE band twenty-five (25) and band sixty-six (66). In this regard, it may be necessary to sufficiently suppress the IMD product(s) in the mobile communication device to achieve desirable user experiences.